foo.cc: In function ‘int main()’:
foo.cc:13:34: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   13 |                 for(int i = 0; i < s.length(); i++)
      |                                ~~^~~~~~~~~~~~
foo.cc:39:29: warning: comparison of integer expressions of different signedness: ‘size_t’ {aka ‘long unsigned int’} and ‘int’ [-Wsign-compare]
   39 |         for(size_t i = 0; i < tips; i++)
      |                           ~~^~~~~~